U.S. patent application number 10/838640 was filed with the patent office on 2004-12-09 for apparatus for monitoring a smoke detector.
Invention is credited to Bobenhausen, Axel.
Application Number | 20040246137 10/838640 |
Document ID | / |
Family ID | 32981195 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040246137 |
Kind Code |
A1 |
Bobenhausen, Axel |
December 9, 2004 |
Apparatus for monitoring a smoke detector
Abstract
The proper function of a smoke detector of an enclosed space,
such as a toilet or freight space or crew quarters in an aircraft,
is monitored by at least two air pressure sensors which are so
positioned that these air pressure sensors can measure an air
pressure differential in the air flow into the smoke detector. If a
pressure differential is detected the differential is evaluated in
a central processing unit which produces a respective signal that
indicates that the air flow and thus the smoke flow into the smoke
detector is obstructed, whereby the smoke detector cannot function
properly. This signal is visibly or audibly indicated.
Inventors: |
Bobenhausen, Axel; (Bremen,
DE) |
Correspondence
Address: |
FASSE PATENT ATTORNEYS, P.A.
P.O. BOX 726
HAMPDEN
ME
04444-0726
US
|
Family ID: |
32981195 |
Appl. No.: |
10/838640 |
Filed: |
May 3, 2004 |
Current U.S.
Class: |
340/606 |
Current CPC
Class: |
G08B 17/10 20130101;
G08B 29/043 20130101; G08B 29/046 20130101 |
Class at
Publication: |
340/606 |
International
Class: |
G08B 021/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2003 |
DE |
103 19 688.9 |
Claims
What is claimed is:
1. An apparatus for monitoring the function of a smoke detector in
an aircraft, said apparatus comprising a smoke detector, an air
flow passage to an air or smoke inlet of said smoke detector, at
least two air pressure sensors positioned in such locations
relative to said air flow passage that an air pressure differential
is detectable in said air flow passage to said smoke detector, a
pressure information evaluating unit operatively connected to said
at least two air pressure sensors for processing said pressure
information to detect an air pressure differential which signifies
that a clogging in said air flow passage to said smoke detector
prevents said smoke detector from functioning properly, and an
indicator for receiving a control signal from said information
evaluating unit for indicating that said smoke detector is
prevented from functioning properly.
2. The apparatus of claim 1, wherein said two air pressure sensors
comprise a first pressure sensor positioned inside said smoke
detector and a second pressure sensor positioned outside said smoke
detector.
3. The apparatus of claim 2, wherein said second air pressure
sensor is positioned upstream of said air or smoke inlet of said
smoke detector in said air flow passage.
4. The apparatus of claim 3, further comprising a hood surrounding
said air flow passage at least partially upstream of said air or
smoke inlet of said smoke detector, said second air pressure sensor
being secured to said hood inside said hood.
5. The apparatus of claim 1, further comprising a third air
pressure sensor arranged inside an enclosure (4) monitored by said
smoke detector.
6. The apparatus of claim 1, comprising an enclosure monitored by
said smoke detector, a protective grid positioned in said air flow
passage to said smoke detector between said enclosure and said
smoke detector, said at least two air pressure sensors comprising a
first air pressure sensor positioned upstream of said protective
grid and a second air pressure sensor positioned downstream of said
protective grid as viewed in an air flow direction toward said
smoke detector, whereby said first and second air pressure sensors
are positioned for detecting a clogging of said protective grid and
thus an impairment of the function of said smoke detector.
7. The apparatus of claim 1, comprising an enclosure monitored by
said smoke detector, a protective grid positioned in said air flow
passage to said smoke detector between said enclosure and said
smoke detector, said at least two air pressure sensors comprising a
first air pressure sensor inside said smoke detector and a second
air pressure sensor inside said enclosure, whereby said first and
second air pressure sensors are positioned for detecting a clogging
of said protective grid and thus an impairment of the function of
said smoke detector.
8. The apparatus of claim 1, wherein said at least two air pressure
sensors comprise a first air pressure sensor positioned downstream
of said air or smoke inlet, and a second air pressure sensor
positioned upstream of said air or smoke inlet, whereby said air or
smoke inlet is positioned between said first and second air
pressure sensors for detecting a clogging of said air or smoke
inlet of said smoke detector.
9. The apparatus of claim 1, wherein said smoke detector comprises
a smoke inlet and a smoke outlet, said air flow passage comprising
a first flow pipe leading to said smoke inlet, a second flow pipe
leading away from said smoke outlet, said first flow pipe
comprising a plurality of holes for smoke to enter into said first
flow pipe for reaching said smoke detector.
10. The apparatus of claim 9, further comprising a smoke discharge
port and wherein said second flow pipe connects said smoke outlet
of said smoke detector to said smoke discharge port for visibly
indicating the presence of smoke in an enclosure monitored by said
smoke detector in said aircraft.
11. The apparatus of claim 1, wherein said apparatus is installed
in a freight space of said aircraft for detecting whether anything
has obstructed said air or smoke inlet of said smoke detector.
12. The apparatus of claim 1, wherein said apparatus is installed
in a position for monitoring any smoke generation in a toilet of
said aircraft.
13. An apparatus for monitoring the function of a smoke detector,
said apparatus comprising a smoke inlet for said smoke detector, at
least one first air pressure sensor arranged downstream of said
smoke inlet, at least one second smoke detector arranged upstream
of said smoke inlet, as viewed in an air flow direction toward said
smoke detector, for detecting an air pressure differential across
said smoke inlet of said smoke detector, a pressure information
evaluating unit operatively connected to said first and second air
pressure sensors for processing a pressure differential information
into a control signal signifying a clogging of said smoke inlet of
said smoke detector, and an indicator for receiving said control
signal for indicating that a smoke detector function is impaired or
prevented.
14. The apparatus of claim 13, further comprising a third air
pressure sensor so positioned relative to said first and second air
pressure sensors that an air pressure differential is detectable
between said first and second air pressure sensors and/or between
said second and third air pressure sensors for providing
information regarding any clogging in an air or smoke flow
passage.
15. The apparatus of claim 13, wherein said first air pressure
sensor is positioned inside said smoke detector.
Description
PRIORITY CLAIM
[0001] This application is based on and claims the priority under
35 U.S.C. .sctn.119 of German Patent Application 103 19 688.9,
filed on May 2, 2003, the entire disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to an apparatus for monitoring a smoke
detector and visually displaying and/or audibly announcing detected
information in an aircraft.
BACKGROUND INFORMATION
[0003] Smoke detectors which are installed, for example in an
aircraft toilet or in a freight space or in crew rest areas, must
be monitored and checked frequently to assure their proper function
when it becomes necessary to detect smoke. Particularly, it is
necessary to monitor an air flow passage that leads to an air inlet
of a smoke detector so that smoke can reach the detector.
[0004] The air flow passage leading to the smoke detector inlet
must not be clogged or otherwise obstructed by being covered,
pasted up or otherwise contaminated so that air and thus smoke can
reach the inlet opening of the smoke detector. The smoke detector
cannot work if the smoke cannot get to the smoke detector. This
clogging may, for example, occur in a protective screen or grid
structure that is positioned in the air flow passage to the
detector, whereby the function of the smoke detector would be
impaired or even prevented.
[0005] It is necessary in all aircraft which by law must be
equipped with smoke detecting devices, to regularly visually
inspect these devices, for example in accessible areas such as
toilets, crew rest areas or the like. These regular inspections
must be made by the crew and must be done frequently, for example
every 15 minutes, particularly on long distance flights. The check
must make sure that the air flow passage or passages leading to the
smoke detector are not obstructed. Thus, it is conventional to
ascertain by an exclusively visual inspection whether the smoke
detectors in the aircraft are prevented from functioning properly,
for example by obstructions that may be a freight container that
has been positioned in front of the air inlet and thus of the smoke
inlet leading to the smoke detector. In areas in which unfiltered
air is circulating such as in a freight space, the air flow passage
leading to a smoke detector may be obstructed or even completely
blocked quite quickly, which leads to impairing or even preventing
the proper function of the smoke detector.
OBJECTS OF THE INVENTION
[0006] In view of the above, it is the aim of the invention to
achieve the following objects singly or in combination:
[0007] to facilitate a continuous monitoring of the smoke detectors
in an aircraft;
[0008] to provide a visual and/or audible indication in response to
the fact that the proper functioning of a smoke detector is
impaired or prevented; and
[0009] to make sure that any kind of obstruction in the air flow
passage of a smoke detector is instantly discovered, for example if
attempts are being made in an aircraft toilet to obstruct the smoke
detector in order to prevent the discovery of cigarette smoke in
the toilet.
SUMMARY OF THE INVENTION
[0010] The above objects have been achieved according to the
invention by arranging at least two air pressure sensors in the
vicinity of each smoke detector. These air pressure sensors are so
positioned within an air flow or smoke flow passage leading to an
inlet of the smoke detector that a pressure differential caused by
an obstruction of the air flow passage results in the detection of
an obstruction within the air flow passage. The output signals of
the air pressure sensors are supplied to an evaluation unit that
may, for example be the central processing unit of the aircraft,
which in turn provides a display signal that may be displayed on a
television screen and/or it may be made audible, thereby signifying
that the function of the smoke detector is impaired or event
prevented by obstructions or clogging in the air flow passage
leading to an air inlet of the smoke detector.
[0011] According to the invention it is an advantage that the smoke
detector or detectors in an aircraft are monitored on a continuous
or permanent basis by making sure that any smoke that is generated
can freely pass to the respective smoke detector inlet without any
flow reduction and without any flow prevention. Another important
advantage of the invention is seen in that a wrong measurement of a
pressure differential in the air flow passage can be prevented by
timing the operation of the air pressure sensors, thereby
preventing an erroneous reaction in case of pressure fluctuation of
very short durations, for example when a vacuum toilet is
activated. Furthermore, it is advantageous that a blockage or
partial clogging of the air flow passage can be automatically
reported to a location outside the enclosure in which the smoke
detector is installed. Thus, the display or indication of the
signal that signifies such a blockage or clogging may be made
visible or audible anywhere within the aircraft, particularly
outside the space in which the smoke detector is installed, such as
a toilet or freight space. The respective signals may be
transmitted to a monitor of a central maintenance system, whereby
the monitor may be located, for example, in the cockpit of the
aircraft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In order that the invention may be clearly understood, it
will now be described in connection with example embodiments
thereof, with reference to the accompanying drawings, wherein:
[0013] FIG. 1 shows schematically an aircraft toilet with a smoke
detector that is monitored according to the invention by three air
pressure sensors;
[0014] FIG. 2 shows an embodiment in which the smoke detector is
monitored by two air pressure sensors and wherein the air flow
passage comprises a perforated pipe leading to the inlet of the
smoke detector; and
[0015] FIG. 3 shows schematically that the air pressure sensors are
electrically connected to a central processing unit for evaluating
the air pressure differential signals.
DETAILED DESCRIPTION OF A PREFERRED EXAMPLE EMBODIMENT AND OF THE
BEST MODE OF THE INVENTION
[0016] FIG. 1 shows schematically an aircraft toilet 4 having a
door 4A in which an air inlet 4B is installed. Arrows A indicate an
air flow passage which is also a smoke flow passage since the air
flow transports any smoke generated in the toilet or within a smoke
detector housing 8 to the smoke detector 7 installed above a toilet
ceiling 5. A protective grid or screen structure 6 separates the
smoke detector housing 8 from the toilet space below the ceiling 5.
The smoke detector housing 8 forms a hood in which normally a fan
is installed for generating the air flow A and an exhaust air flow
B through a used air discharge channel 9 leading out of the smoke
detector housing or hood 8.
[0017] In the example embodiment of FIG. 1, three air pressure
sensors 1, 2 and 3 are installed in the vicinity of the smoke
detector 7 whose air inlet 7A faces into the smoke detector housing
8. One air pressure sensor 1 is installed inside the toilet 4.
Another air pressure sensor 2 is secured to the inner wall 8A of
the smoke detector housing 8. Another air pressure sensor 3 is
installed directly in the smoke detector 7.
[0018] According to the invention two smoke detectors cooperate in
the discovery of a pressure differential that may have been caused
by a clogging or obstruction of the grid or screen structure 6
and/or of the air or smoke inlet 7A of the smoke detector 7. More
specifically, a pressure differential caused by an obstruction of
the air inlet 7A of the smoke detector 7 is sensed by the two air
pressure sensors 2 and 3. A pressure differential across the
protective screen or grid structure 6 is discovered by the air
pressure sensors 1 and 2. A clogging of the air inlet 7A can also
be discovered by the air pressure sensors 1 and 3. In this case the
sensed pressure differential would still correctly indicate that
the smoke detector cannot function properly. However, it would not
be clear whether the inlet 7A or the screen 6 is clogged.
[0019] FIG. 3 shows that the output signals of the air pressure
sensors 1, 2 and 3 are supplied to a central processing unit that
functions in this instance as an evaluation unit of the air
pressure differential signifying signals. The CPU generates an
indication signal that is supplied to an indicator which may be a
television screen and/or a loudspeaker which will provide an
indication that either the screen 6 or the air inlet 7A of the
smoke detector 7 have been partially or completely obstructed or
clogged so that the smoke detector 7 cannot function properly. An
obstruction of the screen or grid structure 6 can be discovered in
two ways. First, the two air pressure sensors 1 and 2 cooperate in
such discovery as mentioned above. Second, the air pressure sensors
1 and 3 can cooperate in discovering a pressure differential across
the screen or grid structure 6 or across the air inlet 7A. In both
instances where the impairment of the smoke detector function is
discovered, it would merely not be clear whether 7A or 6 is
clogged.
[0020] FIG. 2 shows an embodiment in which the enclosed space 4'
may be again a toilet or a freight space or a crew resting area. In
this embodiment only two air pressure sensors 2 and 3 are used. The
sensor 2 is installed in the enclosure 4' while the sensor 3 is
installed inside the smoke detector 7. The smoke detector 7 has an
air inlet 7A and an air outlet 7B. A smoke gathering inlet pipe 10
provided with holes 10A passes through the enclosure 4' and leads
into the air inlet 7A of the smoke detector 7. A smoke outlet pipe
11 is connected to the outlet 7B of the smoke detector 7 and leads
into an outlet box 12 with outlet openings 13 and 14. Thus, any
smoke that has passed through the smoke detector 7 will flow to the
outlet box 12 and out through the outlets 13 and 14 thus providing
a further monitoring possibility by viewing the smoke outlets 13
and 14.
[0021] The number of holes 10A in the smoke gathering inlet pipe 10
is selected so that a sufficient volume of smoke will be gathered
and supplied to the inlet 7A of the smoke detector 7. In this
manner the smoke volume that reaches the smoke detector 7 is
substantially increased compared to the smoke volume that reaches
the smoke detector 7 in the embodiment shown in FIG. 1. Further,
the probability that smoke will reach the detector is increased by
using a plurality of smoke collecting pipes 10. In any event, the
two air pressure sensors 2 and 3 can sense a pressure differential
between the smoke detector 7 and the enclosure 4'. The present
monitoring system can be used in any enclosed space within an
aircraft, for example also in a freight space. As in the first
example embodiment, any kind of obstruction in the air flow passage
to the smoke detector will be discovered, including the obstruction
of the smoke detector inlet by a piece of freight that may have
been placed inadvertently in a position where it can close up the
air inlet of the smoke detector.
[0022] Although the invention has been described with reference to
specific example embodiments, it will be appreciated that it is
intended to cover all modifications and equivalents within the
scope of the appended claims. It should also be understood that the
present disclosure includes all possible combinations of any
individual features recited in any of the appended claims.
* * * * *